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Ch.3 (Final)
Final
Question | Answer |
---|---|
(T/F) Lava is magma on the Earth's surface | True |
(T/F) Extrusive igneous rocks are typically fine grained because they crystallized slowly, deep below the Earth's surface. | False |
(T/F) A dike is a discordant intrusive igneous structure. | True |
(T/F) The geothermal gradient is the rate at which pressure increases with increasing depth beneath the surface. | False |
(T/F) Mafic igneous rocks are silica-poor. | True |
(T/F) A mineral's melting point generally increases with increasing pressure. | True |
(T/F) The sequence in which minerals crystallize in a cooling igneous melt is called Bowen's Reaction Series. | True |
(T/F) A pluton is an igneous structure that crystallized at very shallow depths. | False |
(T/F) Partial melting of the lower continental crust produces a silicic magma that eventually solidifies into granite or rhyolite. | True |
(T/F) An ultramafic rock is composed almost entirely of quartz. | False |
(T/F) The geothermal gradient for a volcanic region is greater than that for the continental interior. | True |
(T/F) Pegmatites are extremely coarse-grained igneous rocks. | True |
(T/F) Basaltic magmas crystallize at higher temperatures than granitic magmas. | True |
Igneous rocks may be either ____ if they form on or near Earth's surface, or ___ if they solidify under ground. | extrusive; intrusive |
______ igneous rocks, like gabbro and basalt, are silica-deficient with high magnesium and iron. | Mafic |
___ is a coarse-grained igneous rock (grains > 1 mm diameter) with visible grains of quartz. | Granite |
Fine-grained igneous rocks (grains < 1.0 mm) that have small grains cooled rapidly and are likely to be _______. | extrusive |
A _______ is a tabular (thin but large area) intrusive body that is concordant (parallel to the host rock structure). | sill |
_____ rocks have coarse crystals in a fine-grained matrix. | Porphyritic |
Both andesite and ___ are composed of feldspars and 30% to 50% ferromagnesian minerals | diorite |
___ are igneous rocks that are silica-deficient but high in iron and magnesium. | Mafic |
Igneous rocks that are silica-rich with high aluminum, sodium, and potassium are _____ rocks. | silicic |
A ______ is an intrusive structure that formed from magma that solidified within the "throat" of a volcano. | volcanic neck |
The most common minerals in a granite are the ______. | feldspars |
______ is the predominant igneous rock of the continents. | Granite |
The melting point of a mineral generally _____ with increasing pressure (or depth). | increases |
Hawaii and __________ eruptions are related to intraplate igneous activity | Yellowstone |
On its slow journey through the crust, mafic magma evolves into intermediate magma by differentiation and assimilation of ______. | silicic rocks |
Most of the basalt and gabbro on the ocean floor is created at mid oceanic ridges, which are also ____. | divergent plate boundaries |
The crust beneath the world's oceans is mafic ________. | basalt and gabbro |
How is a sill different from a dike? | Sills are parallel to the layering in the country rock. |
The coarse-grained equivalent of basalt is a(n) ______. | gabbro |
What type of melting takes place when a body of hot mantle rock moves upward and the pressure is reduced to the extent that the melting point drops to the temperature of the body? | decompression melting |
What is the sequence of crystallization along the discontinuous branch of Bowen's reaction series? | olivine, pyroxene, amphibole, mica |
Viscosity is a property of a fluid that relates to how easily the fluid flows. A material that is viscous __. | flows less easily |
. Imagine two magmas that are identical in all respects (for example, same chemistry, pressure, volume) except that one magma is hotter than the other. Which magma will have the higher viscosity? | The cooler magma will be more viscous. |
What is the process through which magma differentiation takes place? | crystal settling |